CNS 220 Exam 2 Questions and Correct Answers/ Latest Update / Already Graded

What is the ACI and what do they make? Ans: American Concrete Institute, the rule book for concrete What kind of water content is in concrete with high strength but it is difficult to work with? Ans: Lower water content What kind of water content is in concrete with a lower strength but its easier to work with? Ans: Higher water content Why is water the enemy of concrete? Ans: Adding too much can destroy the water to cement ratio, and freeze/thaw cycles can cause it to crack What is an ideal water/cement ratio? Ans: 0.5 or less All rights reserved © 2025/ 2026 | Page | 2 All rights reserved © 2025/ 2026 | What can happen to concrete if the water to cement ratio is above 0.5? Ans: Increased chance of water permeability, a decrease in durability and strength, a decrease in resistance to sulfate, What are the steps to obtain quality concrete? Ans: 1. Proper mixing and proportioning 2. Proper transportation and handling 3. Proper placement 4. Proper Finishing 5. Proper curing How long does concrete last when transporting it? Ans: 90 minutes under normal and cold weather and 45 minutes under hot weather How are concrete structures created? Ans: Build formwork, reinforcing, pouring concrete, finishing and protection How can concrete be placed? Page | 3 Ans: Chutes, conveyors, buggies, pump trucks, wheelbarrow and buckets What does consolidation do in concrete? Ans: Eliminates voids, honeycombs, and air pockets What is the point of a concrete vibrator? Ans: Agitates the concrete to make it flow and eliminate air pockets